Audio problem: In the 9/11/2010 episode there is a scene where Alfie and Roxy have just got back from selling her things to pay for Ronnie's wedding. There is a different audio range from normal speech - Roxy's voice comes across rushed and too loud compared to the other lines she speaks. Also her mouth does not move in sync when she says "So how you feeling about tomorrow, are you nervous?" (00:24:15 - 00:25:00)
Audio problem: In a recent episode where Jane is moving into Ian's place, she accidentally knocks over Ian's daughter's clay vase she made. When you hear the crash, it sounds something like glass shattering on tiles, but it's clay that has fallen on a carpet.
Audio problem: 30/9/10 Throughout the scene when Stacey and Janine are fighting, you can hear the sound effects of thunder and falling rain but you can not see the rain and no one is getting wet.
Audio problem: In series 10, episode 15 Episode 867, transmitted on 25 May 1993, during Nigel's birthday party everyone is dancing and talking loudly to be heard over music - but no music has been dubbed into the scene. The scene lasts several minutes and seems increasingly bizarre as the dancing is energetic and Nigel even takes Debbie to the stairs to talk to her somewhere quieter... But there is no music at all.
Answer: Albert Square is a set in the BBC studios in Borehamwood, on the north side of London. The trains, to the best of my knowledge, are simply a bit of the old TV magic. As far as the extras go - it's not difficult to get extras in reasonable numbers through agencies.
Tailkinker ★